This invention relates to multipurpose dental handpieces, and in particular, handpieces which irrigate and aspirate during endodontic procedures, such as root canal surgery. During endodontic procedures, such as root canals, it is necessary to inject or applicate fluid into the dental pulp or root. Additionally, debris and other matter must be removed from the dental cavity. Presently, typical handpieces used for these types of procedures are designed to spray fluid, under positive pressure, into the tooth cavity. This arrangement has been known to cause a number of difficulties, most notably damage to the tooth cavity caused by undue fluid force.
During a typical root canal procedure, a dental practitioner drills an opening in a patient""s tooth surface enamel and inner dentine to gain access to the dental pulp and surrounding cavity. A hollow, surgical needle is inserted into the opening to both remove decaying pulp tissue by aspiration, and irrigate the cavity with sodium hypochlorite solution. The sodium hypochlorite solution rids the canal of bacteria and other foreign substances before sealant is injected into the canal. The dental pulp cavity is curvately elongate and tapers into the root area of the affected tooth. Common dental practice at this time includes the use of a handpiece fitted with a rigid, stainless steel needle whereby the practitioner alternatively aspirates and irrigates the canal. Several problems are encountered with this arrangement. First, since a stainless steel needle is relatively rigid with respect to the tooth canal and cavity, care must be taken not to puncture the tooth wall and surrounding jaw. Further, access to the extreme distal end of the curved root cavity is not possible due to the rigid nature of the needle. Additionally, the force by which fluid is discharged through the needle can create undue pressure on the tooth walls and surrounding tissue, making full aspiration and irrigation of the canal without damage extremely difficult.
It is therefore an object of this invention to provide an endodontic handpiece assembly capable of irrigating a root canal safely and accurately, while additionally providing aspiration. The handpiece of the invention is provided with means for irrigation and means for aspiration, wherein irrigation is supplied through gravity and surface tension feed. This arrangement lessens the unwanted effects of pressure-applied irrigation while providing the convenience of a dual purpose tool. A control mechanism is disposed on the handpiece, which controls whether fluid dispenses from a fluid discharge nozzle, aspirating vacuum is supplied to a aspiration nozzle, or a combination of irrigation and evacuation is performed.
The assembly further comprises an autoclavable endodontic needle assembly capable of curving to the configuration of a root canal while being inserted therein. The needle of the present assembly may be produced to be pre-bent to a desired angle; the preferred angle chosen is 45 degrees. The needle of the present invention may also be provided with an angle-adjustment sleeve around a portion of the needle to allow for manual adjustment of the pre-bent angle.
It is to be further noted that use of sodium hypochlorite solution as an irritant can be caustic and have an adverse affect on the preferred binary NiTi alloy of the needle. To substantially eliminate the possibility of the solution corroding or deteriorating the NiTi alloy, a coating, such as a parylene polymer, may be applied to the needle during its manufacture. While parylene polymers are the preferred coatings, there are other commercially available coatings that provide similar protection.
It is a further object of the present invention to provide a unique tip for the needle. The tip portion of the present invention includes a skived area at the most distal end of the needle. The skived area allows side venting and prevents vacuum buildup during aspiration of the root canal. The unique tip is further capable of functioning within the narrow and curved confines of a root canal.
The assembly is further provided with an L-shaped connector having two legs. The connector provides communicative connection between both the needle and the aspiration nozzle, and the needle and the discharge nozzle. Each leg of the connector includes a through bore which terminates in an aperture. A third aperture is provided intermediate the ends of the legs. The needle is attached to the handpiece by way of the L-shaped connector and an adhesive-filled supporting hub member which grippingly engages the needle shaft to provide connection to a conventional LUER(copyright) lock. The needle is positioned in one leg of the connector and through its bore, such that an attachment end of the needle is simultaneously positioned through the third aperture.
The needle shaft is thereby grippingly received in one bore leg while its attachment end extends through the third aperture where a supporting hub member supports the attachment end to provide connection with a conventional LUER(copyright) lock. The LUER(copyright) lock is adapted to be received by the aspiration nozzle by way of an interference fit.
The second leg of the L-shaped connector is adapted to receive a flexible tubing length having a through-bore. One end of the tubing is arranged to fit over the second leg aperture while the second end fits over the discharge nozzle. This arrangement allows communication between the discharge nozzle and the second leg of the L-shaped connector. As fluid flows from the discharge nozzle, through the second leg bore it encounters the needle shaft in position in the first leg bore. The fluid then moves out of the first leg aperture along the outside of the needle shaft. The fluid is drawn down the needle shaft and toward the needle tip by surface tension and gravity pull, rather than the positive pressure present in prior art arrangements.